1. Field of the Invention
The invention relates to the field of airborne, hovering, lighter-than-air objects, particularly those having a non-spherical shape.
2. Prior Art
Hot air balloons and helium or hydrogen filled balloons and dirigibles have been known and used for many years for such purposes as entertainment, observation and transportation. The overall principles of physics which govern the flight of such objects have been known for centuries. Balloons used both as toys or for other purposes have often been made from a very thin, light film, such as rubber, paper, etc., and then filled with a lighter-than-air gas or hot air. Usually the shape of the balloon was spherical or nearly spherical and as more gas was added to the balloon, the balloon tended to become more spherical. The reasons for this are that the sphere offers the most efficient shape, that is, it provides the greatest volume for the least surface area, and secondly, because the thin film naturally tends to become spherical as pressure is increased.
In the prior art in lighter-than-air balloons, particularly toy balloons, it has been impossible to fabricate balloons other than those having generally continuously curved shapes. Well-defined corners or edges formed by intersecting plane surfaces or many other esthetic shapes are not practical because they require a supporting frame to maintain the thin film or "skin" in the desired shape. The weight of such frames, even when the most efficient materials for such purposes are selected, requires a displaced volume of such size that fabrication for home use or the like is impractical. Moreover, the problem caused by the weight of the frame is compounded by the fact that the non-spherical shapes are less efficient as lighter-than-air objects since they require more surface material to define a given volume, than does a spherical shape.
The present invention provides a solution to this prior art problem by utilizing a frame fabricated from an epoxy-impregnated graphite fiber material having an extremely high modulus, thus resulting in a much higher strength-to-weight ratio than any other practical rigid material.